Aerofoil stall

This project focused on the numerical study of stall behavior in aerofoils using Computational Fluid Dynamics (CFD). The work aimed to determine the critical angle of attack for both static and dynamic stall conditions and explore the limitations of Reynolds-Averaged Navier-Stokes Equations (RANSE)-based CFD solvers in capturing complex flow phenomena.

Key Objectives :

1. To estimate the stall angle for an aerofoil using RANSE-based CFD.

2. To study the limitations of the RANSE solver as flow separation and turbulence increase at higher angles of attack.

   
   

Methodology :

• Geometric Modeling: The Wortmann FX 79-W-151A aerofoil was modeled and meshed using ANSYS ICEM CFD.

• CFD Simulations: Static and dynamic stall analyses were performed using ANSYS CFX. Dynamic stall was simulated by applying a sinusoidal rotation to the aerofoil.

• Grid Independence: A grid independence study was conducted to ensure accurate and reliable results.

• Validation: CFD results were validated against experimental data, showing close agreement.

Key Findings :

• Static Stall: The stall angle was observed at 12.5°–15° for anticlockwise rotation, while no stall was observed for clockwise rotation within the solver's limitations.

• Dynamic Stall: Dynamic stall conditions resulted in 60–80% higher lift forces compared to static stall, but the solver faced convergence issues beyond 6° in anticlockwise rotation.

• Solver Limitations: The RANSE solver struggled to converge at angles of attack greater than 15° due to excessive turbulence and flow separation, highlighting the need for more advanced solvers like Large Eddy Simulation (LES).

Significance :

• The study demonstrated the effectiveness of RANSE-based CFD in predicting stall behavior for moderate angles of attack.

• It provided insights into the limitations of RANSE solvers in handling high turbulence and flow separation, suggesting the need for more advanced computational methods for higher angles.

• The work contributes to the understanding of aerodynamic stall and offers a foundation for further research using advanced CFD techniques.

This project highlights the potential of CFD as a tool for aerodynamic analysis while emphasizing the importance of solver capabilities in capturing complex flow phenomena.

Tools used : Ansys Fluent, Ansys ICEM CFD, Ansys CFX

Conference : Praphul T. et al., Numerical Study on an Aerofoil Stall, ICEREST, Coimbatore, India (03/2015)

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